This invention relates to strip chart recorders for recording traces representing electrical signals, such as are used in medical and scientific applications. Such instruments include a pen or stylus driven in one dimension by a galvanometer motor responsive to the signal to be measured and a motor-driven drive roll for moving paper under the stylus in a direction perpendicular to the motion of the stylus, so that the paper provides a record of the stylus position, and therefore the signal, over time. The various elements including the stylus motor and the paper drive motor, and the drive roll are mounted on a rigid chassis.
Ordinarily, the paper drive includes a nip roll that is biased by a separate spring assembly against the drive roll to form the paper drive nip. An additional spring assembly is employed in the latch mechanism for securing the door of the paper supply compartment. These constructions require numerous separate parts and careful assembly procedures.